Soap product



Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware N Drawing.Application April 22, 1938, Serial No. 203,638

13 Claims.

This invention relates to novel soap products. More particularly, itrelates to soap products in the form of sheets or films which areadapted to be used individually for a single washing of the hands orface.

It has been proposed heretofore to prepare soap in the form of thinperforated sheets or tablets such that a single piece may be torn offfor use in each washing operation. Soap sheets of this type, however,have numerous disadvantages which are inherent in the physicalproperties of soap. They are brittle and fragile and are thus not welladapted to be carried about by the user nor for dispensing in lavatorieswithout excessive breakage and crumbling. Moreover, it'is difficult tomanufacture soap in thin sheets of this kind for much the same reasons.It has also been proposed to prepare soap leaves by passing continuoussheets of tissue paper through a hot soap solution, scraping ofi theexcess soap from the surface of the paper and then drying. In soapsheets of this kind it is possible to secure only a relatively thincoating of soap, otherwise the soap will tend to break and flake offupon flexing of the sheets. Moreover, when such sheets are used thepaper base forms an objectionable insoluble residue.

It is an object of the present invention to provide an improved soapproduct; a further object is to provide soap products in the form offlexible self-sustaining sheets which are completely and readily solublein water; a further object is to form soap sheets which contain apredominating proportion of soap. Still other objects of the inventionwill be apparent from the ensuing description of my invention.

The foregoing and related objects are accomplished in accordance with myinvention by preparing films from soap and a hydrophilic polymerizedvinyl compound. Such films or sheets can be readily prepared by any ofthe known methods for producing synthetic sheeting, for example bycasting aqueous solutions of soap and the polymerized vinyl compound ona suitable support and drying to form a film, or by extruding such asolution or paste through a fiat nozzle.

The term "hydrophilic polymerized vinyl compound, is used herein and inthe appended claims to include polyvinyl alcohol and such derivativethereof as are soluble or self-dispersible in wet r. Such derivativesinclude the partial esters} ethers and acetals of polyvinyl alcoholwhich con ain sufficient free hydroxyl groups in the moi cule to bewater-soluble. Such derivatives maybe prepared by the partialsaponification or hydrolysis of polyvinyl esters, polyvinyl ethers andpolyvinyl acetals. Conversely, they also may be prepared by the partialreaction of polyvinyl alcohol with acids, aldehydes or other reagentswhich react with hydroxyl groups. In general, those partial derivativeswhich contain from about 65% upward of free hydroxyl groups are solublein water and adapted for use in the present invention. The preferredhydrophilic polymerized vinyl derivatives, for the purposes of thepresent invention, are the partial esters of polyvinyl alcohol whereinabout 4% to 25% of the hydroxyl groups in the molecule have beenesterified. In general I prefer to use partial acetates of polyvinylalcohol having saponification numbers of from about 50 to 250,corresponding to about 5% to 25% esterification of the hydroxyl groups.Such partial esters have the advantage of being more quickly soluble inwater, especially in cold water, than the pure polyvinyl alcohols ofcorresponding degree of polymerization.

Practically any type of soap may be used in I preparing the products ofthe invention, although it is usually preferred to utilize a good gradeof toilet soap. Also, I may use any of various soap equivalents orsubstitutes which are known in the art. For example, I have preparedhighly satisfactory soap films utilizing, as the soap ingredient, thesulfates of higher alcohols of the type that have in recent years beenintroduced into the trade under various trade names such as Gardinol,Duponol" and others. For the sake of brevity, I use the term soap hereinand in the appended claims to include not only the usual soapsconsisting of alkali salts of fatty acids but also soap equivalents andsubstitutes as, for example, the sulfation and sulfonation product's ofvarious organic alcohols, acids and esters and salts of such products.

Although satisfactory films can be prepared from the soap ingredient andthe hydrophilic polymerized vinyl derivative alone, I us,ual p fer toincorporate therewith a softening sticizing agent which serves toincreasthe fiexig bility and strength of the film. For this purposeglycerol has been found to be very satisfactory although other softeningagents may be used as, for example, glycols, such as ethylene glycol,propylene glycol, butylene glycol and diethylene glycol; also starches,sugars, dextrimsorbitol, glucose-amine, formamide, ethanol formamide andsalts of ethanolamines such as ethanolamine stearate. The glycerol orother softening agent is usually added in an amount equivalent to about2% to of the composition.

If desired, other materials may be added to the composition as, forexample, perfumes, scents, coloring materials, medicinal or germicidalagents.

In general, it is desirable to include as large a proportion of soap inthe sheet as will yield a fllm of satisfactory strength and flexibility.It has been found possible to prepare films containing' up to of soapalthough, for the best physical properties of the films, it is generallypreferable to use a maximum of about 80% of the soap ingredient. Whilethere is no definite lower limit with respect to the proportion of thesoap ingredient, I prefer to utilize at least 50% soap in mycompositions.

As illustrative but not restrictive of the invention the followingexamples are given to show the composition of typical soap sheetsprepared in accordance with the invention:

Partial acetate of polyvinyl alcohol (saponiflcation number 200) 20Example III Ivory soap Partial acetate of polyvinyl alcohol(saponiflcation number 200) 19 Glycerol 4 Example IV Duponol AW(sulfated lauryl alcohol) 'l5 Partial acetate of polyvinyl alcohol(saponification number 200) 18 Glycerol 7 Example V Kirk's Cocoa soap 38Kirks Tallow soap 38 Partial acetate of polyvinyl alcohol(saponification No. 15 Glycerol 9 The soap films of the above exampleswere prepared as' follows:

The dried and finely powdered soap was mixed with a 5% aqueous solutionof the polyvinyl alcohol (or partial acetate of polyvinyl alcohol). Inthe examples where glycerol was used, this was added at the same time.The resulting mixture was slowly heated with stirring until the soap wasdissolved and the temperature had reached approximately 70 C. A layer ofthe solution about 0.02 inch in thickness was then spread on a castingplate and dried at a temperature of 70 C. In all cases a flexible filmof excellent mechanical properties was obtained. The film produced inExample I, where pure polyvinyl alcohol was used, was somewhat lesssatisfactory than the other films, in that it was more slowly soluble inwater, particularly in cold water. All of the other films .-showedexcellent water-solubility in addition to satisfactory strength andflexibility. In all cases a sheet about two inches square provided anample supply of soap for a single washing of the hands and face. Sheetsof the type shown in Example IV, wherein a sulfated higher alcohol isutilized as the detergent ingredient, are particularly adapted for usein hard water inasmuch as they do not form insolublesoaps with calciumand ma nesium salts.

Soap sheets prepared in accordance with the invention may be cut intosheets two or three inches square and a number of the sheets bound intobooklets which may be conveniently carried .in the pocket or purse. Atthe time of use, it is 6 necessary only to tear a sheet from thebooklet. The sheets may also be made in the form of continuous stripswhich may be wound on reels for installation in a suitable dispensingdevice in lavatories. The desired length of strip may be cut or torn offat the time of use; if desired, suitable perforations may be provided atintervals along the length of the strip to facilitate tearing.

Although the present invention is primarily concerned with theproduction of flexible soap sheets such as just described, it is notrestricted thereto. Thus, I have found it to be of considerableadvantage to incorporate hydrophilic polymerized vinyl compounds in soapwhich is to be formed 20 into the usual cakes, bars, or tablets. Thehydrophilic vinyl compounds serve to improve the strength of the cakes,rendering them less susceptible to breakage when worn thin, and toretard drying out and cracking resulting therefrom. In addition, themodified soaps have a pleasing texture and improved detergentproperties.

It is to be understood that the invention is not restricted to any ofthe specific proportions, procedures, or ingredients describedhereinabove but includes all such variations, modifications andequivalents as fall within the scope of the appended claims.

I claim:

1. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent and a hydrophilicpolymerized vinyl compound. I

2. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent and polyvinyl alcohol.

3. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent and a partial ester ofpolyvinyl alcohol wherein from about 4% to 25% of the 4! hydroxylradicals are esterified.

4. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent and a partial acetateof polyvinyl alcohol having a saponiflcation number of from about 50 toabout 250. V

5. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent, a hydrophilicpolymerized vinyl compound and a plasticizer therefor.

6. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent, polyvinyl alcohol anda plasticizer therefor. u

7. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent, polyvinyl alcohol andglycerol. v 8. A flexible self-sustaining water-soluble sheet havingdetergent properties comprising soap as a 6 major constituent, a partialester of polyvinyl alcohol wherein about 4% to 25% of the hydroxylradicals are esterifled, and a plasticizer therefor.

9. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a 7 major constituent, a partial ester ofpolyvinyl alcohol wherein about 4% to 25% of the hydroxyl radicals areesterifled, and glycerol.

10. .A flexible self-sustaining water-soluble sheet havingdetergentproperties comprising soap as a 1 major constituent, a partial acetateof polyvinyl alcohol having a saponiflcation number of from about 50 toabout 250 and a plasticizer therefor.

11. A flexible self-sustaining water-soluble sheet having detergentproperties comprising soap as a major constituent, a partial acetate ofpolyvinyl alcohol having a saponification number of from about 50 toabout 250. and glycerol.

12. A flexible self-sustaining water soluble sheet 10 having detergentproperties comprising about ber from about 50 to about 250.

13. A flexible self-sustaining water-soluble sheet having detergentproperties comprising about 50% to 80% soap, 10% to 50% of a partialacetate of polyvinyl alcohol having a saponiflcation number from about50 to about 250, and about 2% to 10% of glycerol.

